Jet Turbine Fuel Compositions and Methods of Making and Using the Same

ABSTRACT

Formulated jet turbine fuels and methods of forming the same are described herein including a method of manufacturing a jet turbine fuel that includes hydrocarbon fluids.

FIELD

The present disclosure generally relates to jet turbine fuelformulations. Specifically, the present disclosure relates to thecombination of hydrocarbon streams and hydrotreating certain hydrocarbonstreams to manufacture jet turbine fuels having specificcharacteristics.

BACKGROUND

Typically, jet turbine fuels are refined using traditional methods tomeet certain specifications. These traditional refining methods producejet turbine fuels that may not optimize the performance of the jets andother vehicles powered by those fuels.

SUMMARY

[We will fill this in once we get claims]

BRIEF DESCRIPTION OF DRAWINGS

These need to be revised.

FIG. 1 illustrates distillation curves for blend stocks.

FIG. 2 illustrates distillation curve data of formulated jet turbinefuels.

FIG. 3 illustrates density data for formulated jet turbine fuels.

FIG. 4 illustrates distillation curve data of blend stocks.

FIG. 5 illustrates distillation curves of jet turbine fuels.

FIG. 6 illustrates density data for formulated jet turbine fuels.

FIG. 7 illustrates hydrogen content for formulated jet turbine fuels.

FIG. 8 illustrates the net heat of combustion for formulated jet turbinefuels.

FIG. 9 illustrates distillation curve data of formulated jet turbinefuels.

DETAILED DESCRIPTION Introduction and Definitions

A detailed description will now be provided. Each of the appended claimsdefines a separate invention, which for infringement purposes isrecognized as including equivalents to the various elements orlimitations specified in the claims. The disclosure that followsincludes specific embodiments, versions and examples, but the disclosureis not limited to these embodiments, versions or examples, which areincluded to enable a person having ordinary skill in the art to make anduse the methods and compositions of matter disclosed when theinformation in this disclosure is combined with available informationand technology.

Various terms as used herein are shown below. To the extent a term usedin a claim is not defined below, it should be given the broadestdefinition skilled persons in the pertinent art have given that term asreflected in printed publications and issued patents at the time offiling. Further, unless otherwise specified, all compounds describedherein may be substituted or unsubstituted and the listing of compoundsincludes derivatives thereof.

Further, various ranges and/or numerical limitations may be expresslystated below. It should be recognized that any ranges include iterativeranges of like magnitude falling within the expressly stated ranges orlimitations.

Certain embodiments of the present invention relate to formulated jetfuel or jet turbine fuel. These terms are used interchangeably and referto fuel used to power jet turbines, such as are used on airplanes,helicopters, and tanks.

Many of the current users of jet fuel use a jet fuel that meets theJP-4, JP-5, JP-8, Jet-A1, or Jet-A specification. Certain relevantchemical and physical property specifications for certain jet fuels areshown in Table 1 below.

TABLE 1 Property JP-4 Limit JP-5 Limit JET-A ASTM Method Fuel Evaporated— 205 max 205 max D-86 10% (° C.) Fuel Evaporated 100 max — — D-86 20%(° C.) End Point (° C.) 270 max 300 max 300 max D-86 Density at 15° C.0.751-.802 0.788-0.845 0.775-.840 D-1298 g/ml Sulfur (ppm) 4000 max 4000max 3000 max D-4294 Mercaptan Sulfur 20 max 20 max 30 max D-3227 (ppm)Freezing Point −58 max −−46 max −40 max D-2386 (° C.) Net Heat of 18,400min 18,300 min 18,400 D-3338 Combustion (BTU/lb) Aromatics (vol %) 25max 25 max 25 max D-1319 Hydrogen content 13.5 min 13.4 min — D-3343 (wt%) Flash Point (° F.) 140 min 140 min 100 min D-93 (60° C.) (60° C.)(38° C.) Smoke Point mm 20 19 25 D-1322

Traditionally, jet fuels and turbine fuels are derived from refinedkerosene. Kerosene is generally obtained from the fractionaldistillation of petroleum between 140° C. and 275° C., resulting in amixture of molecules with carbon chains lengths between 10 and 25 carbonatoms. Unlike traditional methods of manufacturing jet fuels, the fuelsof the certain embodiments of the present disclosure are formulated byblending one or more hydrocarbon fluids to form formulated fuel.

As used herein, the term “hydrocarbon fluids” is used in a generic senseto describe a wide range of materials used in an equally wide range ofapplications. The hydrocarbon fluids generally utilized for theformulated jet fuels described herein may be produced by a number ofprocesses. For example, hydrocarbon fluids can be produced from severehydrotreating, deep hydrotreatment or hydrocracking to remove sulfur andother heteroatoms or polymerization or oligomerization process, suchprocesses being followed by distillation to separate them into narrowboiling ranges. In some cases there may be additional steps, such aschemical or physical separation in order to concentrate a stream intoisoparaffins or paraffins. Further, isoparaffins derived fromoligomerization may constitute hydrocarbon fluids.

Certain hydrocarbon fluids are described in U.S. Pat. No. 7,311,814 andU.S. Pat. No. 7,056,869, which are incorporated by reference herein.Unlike fuels, hydrocarbon fluids tend to have a narrow boiling pointrange, e.g., less than 500° F. (260° C.), or 300° F. (148° C.) or 100°F. (37° C.), for example. Such narrow cuts provide a more narrow flashpoint range and provide for tighter viscosity, improved viscositystability and defined evaporation specifications, as shown by thedistillation curve, for example.

In certain embodiments, the hydrocarbon fluids may be produced byhydrocracking a vacuum gas oil distillate followed by fractionatingand/or hydrogenating the hydrocracked vacuum gas oil. Such fluids mayhave an ASTM D86 boiling point range of from 212° F. (100° C.) to 752°F. (400° C.), wherein the individual hydrocarbon fluids may have thenarrower boiling ranges described herein. The fluids may further have anaphthenic content of at least 40 wt. %, or 60 wt. % or 70 wt. %, forexample. The fluids may further have an aromatics content of less than 2wt. %, or 1.5 wt. % or 1.0 wt. %, as examples. The fluids may furtherhave an aniline point below 212° F. (100° C.), or 205° F. (96° C.) or200° F. (93° C.), for example.

In certain embodiments, the hydrocarbon fluids have low sulfurconcentrations e.g., less than 30 ppm, or less than 15 ppm or less than3 ppm, aromatics contents that are below 1.0 vol. %, or 0.5 vol. % or0.1 vol. %, for example, relatively high net heats of combustion, andnarrow distillation ranges. Further, depending on how the hydrocarbonfluid is processed and produced, the hydrocarbon fluid may be furthercharacterized as predominantly paraffinic, isoparaffinic, or naphthenic(e.g., greater than 40 wt. %, or 50 wt. % or 60 wt. % or 80%). Whilesuch characterization may be helpful in blending to achieve desireddensities and/or high net heats of combustion, such characterization isnot a necessary condition for formulation of jet fuels.

Some illustrative, non-limiting chemical and physical property rangescharacterizing various hydrocarbon fluids are shown in Table 2 below.

TABLE 2 Property Range ASTM Method End Point (° F.) 250-600 or <525 D-86(121-315° C. or <273° C.) Specific Gravity (60° F.) 0.760-0.825 or0.79-0.81 D-1298 Sulfur (ppm) 0.1-5.0 or <3 D-5623 Mercaptan Sulfur(ppm) <1 or <0.5 D-3227 Freezing Point (° F.) −120 to −40 (−84 to −40°C.) D-2386 Net Heat of Combustion >18,250, >18,600, >18,750 D-240(BTU/lb) Aromatics (vol %) 0-1.0 D-1319 Olefins (vol %) 0-0.1 D-1319Hydrogen content (wt %) 13.0-15.3 D-3343 Flash Point (° F.)130-225, >140 (54-107° C., D-93 >60° C.)

The hydrocarbon fluids can be derived from any suitable startingmaterial that can result in materials that meet the final userequirements. It is to be noted that starting materials need not fallinto final product boiling range, as in the gas oil case stated above.Thus, starting materials for production of hydrocarbon fluids can be gasoils or other high molecular weight material (that are furtherhydrocracked to lower molecular weight materials or deep hydrotreated todecrease sulfur content, materials that are normally classified asdistillates, such as kerosene, straight run diesel, ultralow sulfurdiesel, coker diesel (with sufficient hydroprocessing), or light cycleoil from FCC units, for example. Starting materials can be kerosene orgas oils from Gas to Liquid process or from biomass conversionprocesses. Additionally, the starting materials may be olefins toproduce the hydrocarbon fluids, olefins being polymerized oroligomerized. In one or more embodiments, the starting materials mayinclude propene, butene or combinations thereof, for example. In certainembodiments, hydrocarbon fluids can include gas oil, kerosene, straightrun diesel, ultralow sulfur diesel, coker diesel, light cycle oil,hydrodewaxed gasoil or kerosene cuts, ethylene, propene, butene orcombinations thereof.

In one or more embodiments, the hydrocarbon fluids are generallycomponents selected from C₉-C₁₈ or narrower distillation cuts. Specific,non-limiting, examples of distillation cuts characterizing hydrocarbonfluids that may be blended to form the formulated fuels includeSPIRDANE® (e.g., D-40 having a density of about 0.790 g/mL, a boilingrange of 356° F.-419° F. (180-215° C.), flash point of 107.6° F. (42°C.) and D-60 having a density of about 0.770 g/mL, a boiling range of311° F.-392° F. (155-200° C.), flash point of 145° F. (62° C.)), KETRUL®(e.g., D-70 having a density of about 0.817 g/mL, a boiling range of381° F.-462° F. (193-238° C.), flash point of 160° F. (71° C.) and D-80having a density of about 0.817 g/mL, a boiling range of 397° F.-465° F.(202-240° C.), flash point of 170.6° F. (77° C.)), HYDROSEAL® (e.g., G232 H) and ISANE IP® fluids, commercially available from TOTAL FLUIDES,S.A., ISOPAR™ fluids, commercially available from ExxonMobil ChemicalCorp. and IP2835, commercially available from Idemitsu Corp.

With the information and methods provided in this disclosure, it ispossible to formulate a jet fuel with particular desired characteristicsby blending hydrocarbon streams. In one or more embodiments, theformulated fuels include two or more hydrocarbon fluids. For example, insome embodiments, the formulated fuels include two hydrocarbon fluids.In other embodiments, the formulated fuel includes three hydrocarbonfluids. In still other embodiments, the formulated fuel includes fourhydrocarbon fluids. Individual hydrocarbon fluids are chosen forformulation into fuels depending on how each contributes to the finalproperties of a jet fuel blend.

In one or more embodiments, the formulated fuel is formulated to exhibita particular distillation curve or aspects of a particular distillationcurve. For instance, in certain embodiments, the formulated fuel may bedesigned to have a front end within the fuel evaporated limitsdesignated in Table 1 and an endpoint at or below the temperature of theendpoint specified in Table 1. In such an instance, a plurality ofhydrocarbon fluids may be blended to create a formulated fuel that meetsthe jet fuel specifications for “fuel evaporated” and “end point.”

It is not necessary for the individual hydrocarbon fluids that are to beblended to each have particular fluid characteristics, such as end pointor fuel evaporated, within the specification desired. That is, theformulated fuel may be formulated from a broad spectrum of hydrocarbonfluids that in and of themselves do not meet the desired specification.Further, known jet fuel formulations may be incorporated with thehydrocarbon fluid. By utilizing such combinations, a broader tailoredproperty distribution is achievable. For example, a specific,non-limiting formulated fuel may be formed of a first hydrocarbon fluidhaving an end point higher than the desired specification while a secondhydrocarbon fluid may have an end point below that of the desiredspecification to achieve a blend that has an end point that falls withinthe desired specification. Further, by selecting the individualhydrocarbon fluids, it may be possible to replicate a desireddistillation curve within an acceptable margin.

While in certain circumstances a single hydrocarbon fluid may be used asa fuel, such as one that falls within or overlaps the distillation rangefor a particular fuel specification, the combination of two or morefluids results in greater flexibility in how closely it is possible tomatch the entirety of the desired distillation curve and property range.For instance, when matching two points within the specification for agiven fuel grade distillation curve, for example the 10% and finalpoint, it may not be necessary to match the entire JP-5, JP-4, JP-8,Jet-A1, or Jet-A fuel curve to be within the specification. However, bycombining two or more hydrocarbon fluids, it is possible to achieve aformulated fuel that more closely matches the desired distillationcurve, thereby improving performance or standardizing performance, forinstance.

In addition to blending hydrocarbon fluids to reach certain points on adistillation curve, such as the fuel evaporated 10% and endpoint,hydrocarbon fluids may be blended to achieve numerous othercharacteristics. For instance, hydrocarbon fluids may be blended toachieve formulated fuels with certain cold flow properties such as pourpoint, cloud point, freeze point and viscosity. In other embodiments,hydrocarbon fluids may be blended to achieve certain fuel performancecharacteristics, such as density, hydrogen content, and net heat ofcombustion.

As an example, in some embodiments, hydrocarbon fluids that have a flashpoint below the JP-5 specification of 140° F. (60° C.) may be used inthe formulation, but only in amounts that do not reduce the flash pointof the final blend below the specification. Similarly, fluids withfreeze points above the (−46° C.) maximum specification, such as thosewith a minor amount of aromatics, may be included in the blend as longas the final freeze point is below the JP-5 fuel specification value.

The use of hydrocarbon fluids from which aromatics have beenreduced/removed yields another benefit to the fuel. In certainembodiments, the reduced amount of aromatics in the hydrocarbon fluidcomponents leads to a higher net heat of combustion for the hydrocarbonfluids components used as blend stock. In certain embodiments, thecombination of these high net heat of combustion hydrocarbon fluidsresults in a product that exceeds the 18,300 BTU/pound minimumspecification of JP-5 fuel. In certain embodiments of the presentdisclosure, the net heat of combustion is greater than 18,300 BTU/lb orfrom 18,500 BTU/pound to 19,000 BTU per pound as measured by ASTM D-240.In other embodiments of the present disclosure, the net heat ofcombustion is between 18,700 BTU/pound to 18,900 BTU/pound as measuredby ASTM D-240. Further, the use of hydrocarbon fluids from whicharomatics have been removed or reduced may also increase hydrogencontent of the formulated fuel.

In addition, isoparaffinic blend stocks may help to raise thegravimetric net heat of combustion when included in the blend, as suchblend stocks' net heat of combustion is greater than aromatics ornaphthenics that are characterized by the same carbon number. Normalparaffin blend stock may also raise the net heat of combustion.

Density is an important parameter of the fuel as it affects the weightof the fuel that can be lifted by the vehicle and the sortie range.Within the framework of the desired distillation curve, hydrocarbonfluids may be chosen to alter the density of the final blend. Forexample, naphthenic based fluids will tend to raise the final densitywhile isoparaffinic fluids tend to reduce the density of the finalproduct. Materials that contain a significant amount of naphthenes andare at the high end of the distillation curve relative to a fuelspecification such as JP-5, such as HYDROSEALS®, can be used to increasethe density of the blended product. In certain embodiments of thepresent disclosure, the density at 15° C. is between 0.77 and 0.82,between 0.799-0.815, between 0.81 to 0.850, and between 0.77 to 0.80, asmeasured by D-1298.

Accordingly, one or more embodiments utilize isoparaffin hydrocarbonfluids as at least one of the two or more hydrocarbon fluids. In one ormore embodiments, the fuel may include a first hydrocarbon fluid havinga density greater than 0.8 g/ml and a second hydrocarbon fluid having adensity less than 0.8 g/ml, for example. The formulated fuels may have aweight that is about 5%, or 7% or 9% less than the weight of the JP-5fuel, for example.

Hydrogen content of the fuel has a significant effect on the performanceof the fuel. Generally, the higher the hydrogen content, the lower themolecular weight of the combustion products and the higher the exhaustvelocity. The motion impulse of a jet engine is equal to the fluid massmultiplied by the velocity of the exhaust gas. However, as the vehiclemoves forward, the fluid moves toward it creating an opposing ram drag.Thus, the net thrust is proportional to the difference between thevehicle velocity and the exhaust velocity. This implies that the vehiclecannot accelerate past its exhaust velocity. One way of maximizing thisvelocity difference is to reduce the molecular weight of the exhaustgases. Theoretically, this additional exhaust velocity would facilitatea greater top speed for the aircraft.

In certain embodiments of the present disclosure, the hydrogen contentof the formulated fuel is controlled by increasing the ratio of hydrogento carbon atoms of the molecules of the hydrocarbon fluid blend stocks.For instance, reducing rings and branching and increasing the degree ofhydrogen saturation of hydrocarbon molecules increases thehydrogen:carbon atom ratio, thereby increasing hydrogen content of thefuel. Removing or reducing aromatics in the hydrocarbon fluid blendstocks may result in a significant increase in hydrogen content.Hydrogen content in certain embodiments of jet fuel of the presentdisclosure are greater than 13 wt %, from 14.25-15.5 wt %, from 14-14.8wt %, less than 15.3 wt %, and between 14.8 and 15.5 wt % as measured byASTM D-3343, compared to the JP-5 specification of 13.4%.

Typically, the hydrocarbon fluids used in the blended formulated fuelhave very low sulfur concentration. Sulfur adversely affects fuelperformance in a number of ways, including reducing the net heat ofcombustion and increasing fouling. Therefore in some embodiments, theformulated fuels include significantly reduced sulfur contents comparedto conventional jet fuels. For example, the formulated fuels may includeless than 30 ppm or less than 5 ppm sulfur. In other embodiments, theformulated fuels contain less than 3 ppm sulfur or less than 1 ppmsulfur.

Due to the significant absence of olefins and aromatics from theformulated fuel, the formulated fuels exhibit improved thermal stabilityover a traditionally manufactured jet fuel. Engines utilized in thevehicles described herein may utilize jet fuel in order to cool engineparts. These parts periodically foul, in large part due to aromaticsand/or olefins present in the fuel. Accordingly, the formulated fuelsprovide a fuel that may allow a reduced maintenance schedule to berealized without any loss in performance.

Further, the absence of olefins and aromatics will result in improvedsmoke point performance of the fuels. In ASTM D-1322, a reference fuelcontaining 25% (volume) toluene and 75% (volume) isooctane is expectedto have a smoke point of 20.2 mm. In certain embodiments of the presentdisclosure, the smoke point of the formulated fuel exceeds 25 mm and inother formulations is 30 mm or more. As formulated, the jet fuelsdescribed herein are characterized by no measurable aromatics by ASTMD-1319. Thus, use of these fuels is expected to result in cleaner engineoperation, elimination of soot and particulate emissions, and theelimination of a telltale trail behind military jets.

The formulated fuels of the present disclosure overcome problems ofcertain traditional jet fuels' performance by blending existinghydrocarbon fluids to produce a fuel at least equal in properties, ifnot superior to, traditionally manufactured jet fuels. Further, theformulated fuels of the present disclosure can be tailored to provideproperties such as density, hydrogen content, and heat of combustion.

In other embodiments of the present disclosure, jet turbine fuels areformed from a single hydrocarbon fluid. In these embodiments, the singlehydrocarbon fluid is hydrotreated to remove sulfur and mercaptans, aswell as to saturate aromatics that are present in the hydrocarbon fluid.

It is further contemplated that the formulated fuel may contain variousadditives, such as dyes, antioxidants, metal deactivators, andcombinations thereof, for example.

Examples

Samples of various formulated fuels were analyzed by D-86, density,aniline point, cloud point, sulfur content, and aromatics content byFIA. The distillation curve and density were used to calculate hydrogencontent by ASTM D-3343. The distillation curve, density, aniline point,sulfur content, and aromatics content were used to calculate the netheat of combustion by ASTM D-4529. The density was measured at 15° C.,as required by ASTM D-4529, which is an estimation of the net heat ofcombustion. Subsequent density measurements made on formulated fuelswere done on the same basis. The latter was used to calculate the netheat of combustion.

The materials analyzed for use in the formulated fuels were SPIRDANE®D-40, SPIRDANE® D-60, KETRUL® D-70, KETRUL® D-80, HYDROSEAL® G 232 H,ISANE IP®175, and ISANE IP®185. The distillation curves for thesecomponents are shown in FIG. 1. None of the individual componentsexhibit a full range distillation curve and could not be used “as is,”i.e. without formulation. The components were either high boiling, aswas the G 232H, low boiling, like the D-60, or characterized by anarrower boiling range, like the D-80. However, this combination ofattributes for the blend components allows flexibility in blending asthe front, middle, and back end of the distillation curve for the fuelcan be tailored to match a desired specification. Alternatively, variouscharacteristics of the fuel relating to the distillation curve or otherproperties can be optimized through the appropriate selection ofcomponents for blending.

The density measurements for all components excluding the ISANE IP®materials were close to that of the traditionally manufactured jet fuel.ISANE IP® materials were characterized by a lower density than that ofthe traditionally manufactured jet fuel. The net heats of combustion andhydrogen content for those components, including ISANE IP® materials,were comparable to the traditionally manufactured jet fuel.

Once component data was compiled, the formulated fuels were made. Anumber of prototype blends were made to gauge how the componentsaffected each other in combination. Three prototypes were made anddesignated proto-6, proto-7, and proto-8. Proto-6 was designed to have atraditional kerosene distillation curve. Proto-7 and proto-8 weredesigned to be lower boiling and higher boiling than standard fuel, onaverage, respectively. The latter two were made to determine what rangeof density and other properties would be achievable with the currentblend components, such as SPIRDANE®, KETRUL®, and HYDROSEAL® basedmaterials if the limits of the distillation curve were pushed. Blendformulations for the prototypes are shown in Table 3.

TABLE 3 Blend Formulation D-60 (vol %) D-70 (vol %) D-80 (vol %) G232H(vol %) Proto-6 70 5 0 25 Proto-7 90 5 0 5 Proto-8 45 0 10 45

The distillation curve data for proto-6, proto-7, and proto-8 is shownin FIG. 2. With specifications only at the 10% and the endpoint, thereis wide latitude in the distillation curve that will meet the JP-5specification. All three prototypes met this specification. Proto-8,designed to be high boiling on average, had a 10% point at 410° F. Allthree had end points below the (300° C.) JP-5 maximum. Proto-7 wassignificantly below it at 465° F. (240° C.), by design.

A high concentration of the light D-60 component reflected in theposition of the proto-7 distillation curve below all others tested.Similarly, the high concentration of the heavy component G232H raisedthe proto-8 distillation curve above all the others.

Cloud point data for all formulations was below the freeze specificationof (−46° C.) JP-5 and −58° C. JP-4 indicating that all have anacceptable freeze point. The sulfur content was measured by wavelengthdispersive x-ray fluorescence, as noted earlier. Prototype formulationswere at the limit of detection for that method with measurements at0.5-0.6 ppm. The density measurements were within the JP-4 and JP-5specifications. The density measurements are compared in FIG. 3.

ISANE IP® 175 and 185 are characterized by densities significantly lowerthan the traditionally manufactured jet fuel, but have flash points thatare at or above that of the JP-5 specification. The density of each ofthese was below 0.77 g/ml, a significant reduction relative to otherblend components and the traditionally manufactured jet fuel.Additionally, the hydrogen content was measured between 15.1 and 15.2.This is in agreement with the theoretical value of 14.9-15.3% for afully saturated sample with no naphthenic rings in the C₁₂ to C₁₈ rangeand as reflected by typical values reported on the certificate ofanalysis for these materials.

The distillation curve data is shown in FIG. 4 for certain hydrocarbonfluids. The new materials are very narrow cuts with end points below400° F. (204° C.). This necessitates the use of a middle and heavy cutin order to create jet fuel formulation. Additionally, the front end ofthe distillation curve was very clean indicating that few very light,low flash point compounds were present making these ideal blendcomponents for the light portion of the formulation. The prototypeblends formulated with the new components were designated proto-9through proto-12. The composition of these blends is shown in Table 4.

TABLE 4 ISANE ISANE Blend D-60 D-70 D-80 G232H IP 175 IP 185 Formulation(vol %) (vol %) (vol %) (vol %) (vol %) (vol %) Proto-6 70 5 0 25 0 0Proto-7 90 5 0 5 0 0 Proto-8 45 0 10 45 0 0 Proto-9 0 10 0 30 0 60Proto-10 0 0 15 20 0 65 Proto-11 0 12.5 0 12.5 75 0 Proto-12 0 15 0 20 065

The distillation curves corresponding to the new formulations are shownin FIG. 5. Proto-9 matched the Proto-6 distillation curve closely.Proto-11 was designed to be a low density fuel, as shown by the ratherhigh concentration of ISANE IP®175 in its formulation. Proto-10 andProto-12 were formulated to contain a greater proportion of middleboiling compounds and examine the difference between the contributionsof D-70 versus D-80 to the distillation curve. As shown, the differencewas minimal for the quantities used.

The immediate effect of the presence of replacing the lower boilingcomponents with isoparaffins can be seen on the density measurement inFIG. 6. The low-density blend proto-11 was measured at 0.7744 g/ml. Thisformulation saves about 800 pounds on the internal fuel load of anF/A-18E fighter. Alternatively, the density can be maximized if desiredas in Proto-8.

The hydrogen content for the prototypes is shown in FIG. 7. Replacingsome of the compounds that are naphthenic in nature with the fullysaturated isoparaffins resulted in a net increase in hydrogen content tonearly 14.9 for proto-9 and to 15 for the low-density formulation,proto-11. This was a significant increase over the 13.4% JP-5specification.

The net heat of combustion for the prototypes is shown in FIG. 8.

In addition to the above proto-formulations, proto-20 was formulated.Proto-20, like proto-6 and proto-9 was designed to match withinreasonable limits a normal distillation curve. FIG. 9 illustrates thedistillation curves for all four formulations. However, proto-20 wasalso designed to provide an intermediate density, hydrogen content, andnet heat of combustion between proto-6 and proto-9. Hence, Proto-20 hasa density at 15° C. of 0.8001, a hydrogen content of 14.51 wt %, and anet heat of combustion of 18,736 BTU/lb.

Samples of proto-6 and proto-20 were measured according to ASTM-D1322 todetermine the smoke point. The smoke point of proto-6 was 30 mm and thatof proto-20 was 31 mm.

In another example, jet fuel was hydrotreated. Conditions of thehydrotreater were:

TABLE 4 Start of run inlet pressure 550 psig Hydrogen circulation 1800SCF per barrel Liquid hourly space velocity 0.82 per hour Hydrogenpurity 95% Inlet temperature (start of run) 640° F. Inlet temperature(end of run) 700° F.

The resulting jet turbine fuel had the following characteristics:

TABLE 5 Aromatics Vol. % ASTM D 1319 17.2 Smoke Point ASTM D 1322 21.0Net Heat of Combustion (BTU/lb) ASTM D 3338 18541 API Gravity ASTM D4052 41.1 Freeze Point (° C.) ASTM D 56 −53 Sulfur (wt %) ASTM D 7039<0.2 ppm Mercaptan (wt %) UOP 163   <1 ppm Distillation 10% D 86 382 EndPoint (° F.) D 86 490

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof and the scope thereof isdetermined by the claims that follow.

What is claimed is:
 1. A method of manufacturing a jet turbine fuelcomprising combining at least two hydrocarbon fluids.
 2. The method ofclaim 1 wherein the jet turbine fuel meets JP-5, JP-4, JP-8, Jet-A1, orJet-A specifications.
 3. The method of claim 1 wherein the hydrocarbonfluids have a specific gravity at 60° C. of between 0.760 and 0.850, asmeasured by ASTM D-1298.
 4. The method of claim 3, wherein thehydrocarbon fluids have a specific gravity at 60° C. of between 0.790and 0.81, as measured by ASTM D-1298.
 5. The method of claim 1, whereinthe hydrocarbon fluids have a sulfur concentration of less than 3 ppm asmeasured by ASTM D-5623.
 6. The method of claim 1, wherein thehydrocarbon fluids have an aromatics content of less than 1% by volume,as measured by ASTM D-1319.
 7. The method of claim 6, wherein thehydrocarbon fluids have an aromatics content of less than 0.1% byvolume, as measured by ASTM D-1319.
 8. The method of claim 1, whereinthe hydrocarbon fluids have an olefins content of less than 0.1% byvolume, as measured by ASTM D-1319.
 9. The method of claim 1, whereinthe hydrocarbon fluids have a hydrogen content of from of greater than13 wt. %, as measured by ASTM D-3343.
 10. The method of claim 1, whereinthe hydrocarbon fluids have a flash point of between 90 and 225° F., asmeasured by ASTM D-93.
 11. The method of claim 1, wherein the jetturbine fuel has a hydrogen content of from between 14.25 to 15.5 wt. %,as measured by ASTM D-3343.
 12. The method of claim 11, wherein the jetturbine fuel has a hydrogen content of from between 14.8 to 15.5 wt. %,as measured by ASTM D-3343.
 13. The method of claim 1, wherein the jetturbine fuel has a net heat of combustion greater than 18,300 BTU/pound,as measured by ASTM D-240.
 14. The method of claim 13, wherein the jetturbine fuel has a net heat of combustion between 18,500 and 19,000BTU/pound, as measured by ASTM D-240.
 15. The method of claim 1, whereinthe density of the jet turbine fuel at 15° C. is from 0.750-0.850, asmeasured by ASTM D-1298.
 16. The method of claim 15, wherein the densityof the jet turbine fuel at 15° C. is from 0.750-0.850, as measured byASTM D-1298.
 17. The method of claim 1, wherein at least one of thehydrocarbon fluids comprises an isoparrafin.
 18. The method of claim 1,wherein at least one of the hydrocarbon fluids comprises a normalparaffin.
 19. The method of claim 1, wherein the jet fuel has anaromatics content of less than 0.1% by volume, as measured by ASTMD1319.
 20. The method of claim 1, wherein none of the hydrocarbon fluidsmeet the JP-5 specification.
 21. A jet turbine fuel comprising ahydrocarbon fluid, wherein the jet turbine fuel has a sulfur content ofless than 1 ppm as measured by ASTM D-7039.
 22. The jet turbine fuel ofclaim 21, wherein the jet turbine fuel has a sulfur content of less than0.5 ppm as measured by ASTM D-7039.
 23. The jet turbine fuel of claim21, wherein the jet turbine fuel has a smoke point of greater than 20 mmas measured by ASTM D-1322.
 24. The jet turbine fuel of claim 23,wherein the jet turbine fuel has a smoke point of greater than 30 ppm asmeasured by ASTM D-1322.